This invention relates generally to friction clutches, and more particularly relates to centrifugal clutches in which the frictional elements engage at a predetermined speed of rotation of a power shaft.
Centrifugal friction clutches which engage at a predetermined rotational speed are particularly useful in combination with internal combustion engines which tend to stall under starting load conditions, by delaying engagement until the engine is operating at a sufficiently high speed to produce enough torque to prevent stalling. One such centrifugal clutch includes a number of plates and discs which move into frictional engagement by pressure exerted by pivoting of weights arranged next to the plates and discs. Such centrifugal friction clutches are also particularly useful in connection with small displacement internal combustion engines such as are used in go-carts, a demanding application of such a clutch in which any unnecessary size and weight can be a disadvantage. Centrifugal clutches are also known in automatic multispeed transmissions, but such transmissions add a considerable amount of size and weight to a small vehicle, and go-carts or one-quarter midget racing vehicles typically are not equipped with transmissions. It is therefore necessary for the clutch to be continually engaged and disengaged.
During normal operation of such a centrifugal clutch, the temperature of the plates can become extremely high, which commonly leads to unnecessary wear, deterioration and warping of the clutch components, requiring frequent replacement of clutch components. For example, during constant operation, the friction plates of such a clutch will often need to be replaced every hour. In order to combat the problem of excessive heating of a clutch, one conventional type of friction clutch utilizes a pressure ring which includes vanes formed on one face of the pressure ring for circulating air through the clutch. Another friction clutch includes a flywheel with vanes for circulating air through the clutch, and air flow fins or guides that may be secured to a supporting plate. In another conventional clutch, a pressure plate is provided with vanes for air cooling of the clutch. It would be desirable to provide one or more plates of an air cooled centrifugal clutch with air impeller vanes. In particular, it is desirable to provide a front pressure plate of a centrifugal clutch with air impeller vanes, but such air impeller vanes can interfere with the operation of weighted levers of the centrifugal clutch. Accordingly, the present invention meets these and other needs.
Briefly, and in general terms, the present invention provides for a centrifugal clutch with one or more clutch plates having a plurality of air impeller vanes to circulate air through the centrifugal clutch during its operation in order to extend the useful life of the clutch.
The present invention accordingly provides for an improved centrifugal clutch for transmission of torque from a rotating input connector for supplying rotational power to an output connector receiving the rotational power, the centrifugal clutch having frictional surfaces adapted to be engaged at a predetermined engagement speed of rotation of the input connector. The centrifugal clutch includes a cylindrical housing drum having a plurality of slots, and a plurality of clutch plates disposed within the cylindrical housing drum operatively engaged with the input connector.
A centrifugal force lever support plate having a plurality of apertures therein is disposed within the cylindrical housing drum, and a pressure plate having a contact friction side and an opposing side, which is disposed within the cylindrical housing drum with the opposing side of the pressure plate adjacent to the centrifugal force lever support plate. The centrifugal force lever support plate is operatively engaged with the input connector, and includes means for applying an adjustable biasing force on the pressure plate toward the centrifugal force lever support plate. The centrifugal force lever support plate also includes a plurality of centrifugal force levers symmetrically disposed on and pivotally attached to the centrifugal force lever support plate, with each of the centrifugal force levers biasing the pressure plate toward the cylindrical housing drum due to centrifugal force exerted on the centrifugal force levers during rotation of the centrifugal force lever support plate. One or more clutch disks are disposed within the cylindrical housing drum adjacent to the pressure plate, with each clutch disk having a plurality of flanges engaging the plurality of slots of the cylindrical housing drum, respectively, and a floating plate may also be provided adjacent to the one or more clutch disks. A fixed plate having a friction contact side is disposed within the cylindrical housing drum between the one or more clutch disks and the cylindrical housing drum, with a friction contact side of the fixed plate disposed adjacent to the one or more clutch disks. A drive hub mounted to the fixed plate is disposed within the cylindrical housing drum, and engages the input connector.
In one aspect, the pressure plate includes a plurality of air impeller vanes formed by alternating raised impeller vane portions and impeller vane channels, with the weighted levers of the centrifugal clutch aligned with the raised portions of the air impeller vanes of the pressure plate. In another aspect, the floating plate may also include a plurality of air impeller channels formed internally within the floating plate and having openings at the outer and inner edges of the floating plate. In another aspect, the fixed plate may also include a plurality of air impeller vanes formed on the side of the fixed plate opposing the friction surface of the fixed plate by alternating raised impeller vane portions and impeller vane channels.
These and other aspects and advantages of the invention will become apparent from the following detailed description and the accompanying drawings, which illustrate by way of example the features of the invention.